Sukveyoe s chaiet



No. 23,630. h

l. M. GRUMMAN.

Surveyor's l Chain. l

Patented April 19,` 1859.

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JOSIAH M. GRUMMAN, OF BROOKLYN, NEV YORK.

SURVEYORS CHAIN.

Specification of Letters Patent N o. 23,680, dated April 19, 1859.

ToaZZ whom 'it may concern:

Be it known that I, JosIAH M. GRUMMAN, of Brooklyn, count-y of Kings, and State of New York, have invented a new plan or method of making Civil Engineers and Surveyors Chains and Attachments; and I do hereby declare that the following is a full and exact description thereof, reference being had to the accompanying drawings and to the letters of reference marked thereon.

The nature of my invent-ion consists of a more compact and correct form of making measuring chains and attachments.

The links, X, Fig. 8, are made of steel wire tempered, of a peculiar form, which peculiarity consists of one eye being of an oval or egg shape--see l/V, Fig. 8,-while the other eye is round. This arrangement gives the following advantages. Theoval eye has length of wire enough to allow the smaller or round eye to be sprung into it thereby avoiding` the use and error of irregular rings. The long slope or sharp end of the eye forms a shoulder, making a kink unusual and if a kink forms it produces an elbow in the chain that will attract attention. Each eye has width enough to allow the chain to fold neatly and easily and each eye has a quick curve at the poi-nt of Contact with the next link which insures the contact in the same place every time the chain may be stretched out.

The forward end of the chain is a springn balance and spirit level combined, Figs. l, 2 and 3. Fitting on the main tube A, is a second tube, B, sliding over it, with a clamp screw C, to tix it at any particular spot.

Vhen not in use, it is clamped over the bubble as a protection. A scale near the forward end of the tube E shows the expansion and contraction of the chain for every ten degrees of the thermometer according to its length (the accompanying drawing is for a fifty feet chain). The scale r'uns from zero to one hundred. The links of the chain are -adjusted when made to be exact at fifty degrees, the mark for which on the scale is placed exactly (F,) the length of a link from the point of contact, Z, with the last link of the chain. The spring balance L, M, is used to give an even tensio-n to the chain and the same sag or curve Fig. 7 if measuring with the chain suspended. The scale Fig. 4 is marked in pound divisions or it the screw l, R, (which is set in the tube A,

and riveted at R, so that it will turn in the tube without vertical motion yet passes through the plate P, on which the bubble rests with a fine thread raising or depressing it as it turns) that when the chain is suspended at its proper tension, the two ends being on a horizontal line Fig. 7, the bubble will center as at D, Fig. l. At the end of the tube next the chain is a spring catch V, attached to the tube by a small link U, Fig. 2, shaped like the ligure 8 placed in a lateral position; by means of this catch the spring balance and level can be attached to any link of the chain at pleasure.

At the back end of the chain Figs. 9 and l0, attached to a steel bar a, is a thermometer c, subject to the same influences of heat' and cold as the bar a. The thermometer c, slides into a metal tube or covering Y), which is soldered fast to two small blocks h, h, which are riveted to the bar a. At a short distance from the. mouth ofthe tube b, is a small block CZ, riveted to the bar a which keeps the thermometer from any chance of falling from the tube of itself; it can be taken out however by simply raising it when withdrawing it from the tube. Exactly the length of a link from the point of contact g, with the first link of the chain is a fine line e, with a notch on each side, from which line starts the measurement.

To measure with the chain the person at the back end of the chain examines the thermorneter previous to measuring and calls out the temperature which may be for instance 7 00. The person at the forward end then sets the slide B, so that the line G, coincides with the 70o mark on the scale E. The hindmost person see Fig. 7, now holds the chain, by means of a plummet and line so that the mark e, is directly over the point he wishes lto measure from, the other then pulls the balance to the adjusted mark and raises or lowers the chain until the bubble centers, when the two ends of the chain are on the same horizontal line, then, keeping the balance still to the mark, vdrops his plummet from the mark Gr, and setting a peg in the point indicated by the plummet moves on until the hindmost person comes to the peg when the same operation is repeated.

What I claim as my invention and desire to secure by Letters Patent is,

l. The method of making civilengineers and surveyors chains of a peculiar form of link as before described and shown.

2. The arrangement of spring balance and level in the same tube or covering With the arrangements for adjust-ing as before described and shown.

3. The method of allowing for the variation of the temperature by a scale of variation on the chain With the adjust-ing slide and clamp, as before described and shown, so that the chain may be virtually shortened or lengthened to meet the temperature.

4. The use of the spring catch by means of which the balance and level is detached from the end link and attached to any other link in the chain at the pleasure of the operator.

5. rlhe method of attaching the thermometer to the end bar of the chain as before described and shown.

J. M. GRUMMAN.

lVitnesses:

WM. H. STONY, ALEX. W. BENNEM. 

